Authorities

It's
remarkably easy for the police and other state authorities to monitor your Internet
activity, including intercepting your emails.

They
do it, too.

Internet
monitoring by police and intelligence services

As a generalization, your
privacy level on the Internet is lower than on a regular phone line.

Internet network managers
can see your emails, companies store information about your visits, and hackers
do whatever they feel like doing.

The police and state security
organisations also take a strong interest in the Internet. In the UK, all Internet
traffic is monitored by an MI5 surveillance centre.
This includes most of the traffic between Europe and the USA.

In theory they're supposed
to get a court order before collecting information on an individual's Internet use and reading their emails, but
if you believe they always do this, you probably also believe in Father Christmas
and tooth fairies.

Most other countries
don't have such a formalised bugging system, but you can be pretty confident
they can follow your Internet use if they feel like it. The NSA in the
US almost certainly monitors thousands of users.

You can make life difficult
for them using encryption. Even the
security services have a problem decoding
encrypted messages. But it's only a problem of time and computing power. They
can decode them if they decide to - it just might take them a while.